The present invention relates generally to dielectrics used as substrates and semiconductors, and more specifically to the incorporation of a silicon carbide or silicon carbide doped barrier layer on a porous low-k dielectric layer.
The integrated circuitry (IC) industry uses dielectric materials having a low dielectric constant (low-k materials) including nanoglass and xerogel materials. While these materials have excellent dielectric properties, such materials also tend to have high porosity. This can cause problems at the metallic interface as layers of metal or metal alloys contact dielectric surfaces. Windows or vias are etched or otherwise fashioned into the dielectric to form interconnects between various dielectric layers. Such vias contain various metals such as copper, tungsten, aluminum, or alloys thereof.
However, such metal layers often have migration problems whereby the various metallic elements leach into, or migrate, into the pores of the dielectric. Such migration can lead to a lack of uniformity in the overall properties of the semiconductor wafer produced. Further, the porous dielectric may allow moisture to creep into the pores. This can cause xe2x80x9coutgassingxe2x80x9d as current is run through the wafer, thus causing a potential circuit failure.
To solve this problem, various barrier layers have been tried which are inserted into the dielectric and positioned between the dielectric and the eventual metal plug. For example, such barrier layers comprise tantalum nitride, titanium nitride, or combinations thereof. Nevertheless, the problems of adhesion and moisture blocking have not been completely solved by the known barriers currently in use.
In one embodiment, the present invention is directed to a dielectric substrate comprising a barrier layer further comprising silicon carbide.
In a further embodiment, the present invention is directed to a silicon carbide barrier layer within a dielectric having an amount of boron-containing compound or elemental boron.
In another embodiment, the present invention relates to a semiconductor comprising a substrate having a conductor and a dielectric formed on the substrate. The dielectric is made from a porous material, preferably a xerogel or nanoglass composition. The dielectric has a via extending through the dielectric and exposing a surface of the conductor. The via and dielectric surface is coated with a silicon carbide-containing material that is preferably doped with boron, and most preferably is SiC(BN) (2 wt % boron). A metal plug is then deposited in the via. Optionally, additional layers may be included in the interconnect between the SiC-containing barrier layer and the metal plug.
In yet a further embodiment, the present invention is directed to a method for inhibiting the introduction of moisture to a porous dielectric substrate. A porous substrate having a conductor is provided, followed by forming a via through the substrate and exposing a surface of the conductor. A SiC-containing material is then deposited onto the substrate and into the via followed by depositing a metal into the via and onto the SiC-containing material.